George Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Quincy. A median date has an even chance of a later freeze in spring, or an earlier one in fall.
The last spring freeze typically comes around April 21 and the first fall freeze around October 16, a growing season of about 178 days.
- Median at 36°F
- last May 3, first October 5
- Median at 32°F
- last April 21, first October 16
- Median at 28°F
- last April 2, first October 27
Last freeze in spring
The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 21 | May 14 | May 10 | May 6 | May 3 | May 1 | Apr 29 | Apr 26 | Apr 22 |
| 32°F | May 5 | May 1 | Apr 28 | Apr 24 | Apr 21 | Apr 18 | Apr 15 | Apr 11 | Apr 5 |
| 28°F | Apr 20 | Apr 14 | Apr 10 | Apr 6 | Apr 2 | Mar 31 | Mar 27 | Mar 23 | Mar 15 |
| 24°F | Apr 3 | Mar 29 | Mar 23 | Mar 18 | Mar 14 | Mar 11 | Mar 7 | Mar 3 | Feb 25 |
| 20°F | Mar 17 | Mar 10 | Mar 5 | Mar 1 | Feb 26 | Feb 21 | Feb 14 | Feb 6 | Jan 28 |
| 16°F | Mar 2 | Feb 26 | Feb 19 | Feb 13 | Feb 7 | Feb 3 | Jan 28 | Jan 18 | Jan 6 |
First freeze in fall
The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 27 | Oct 1 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 16 |
| 32°F | Oct 4 | Oct 8 | Oct 12 | Oct 14 | Oct 16 | Oct 19 | Oct 21 | Oct 24 | Oct 27 |
| 28°F | Oct 16 | Oct 19 | Oct 23 | Oct 25 | Oct 27 | Oct 29 | Nov 1 | Nov 3 | Nov 9 |
| 24°F | Oct 23 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 18 | Nov 25 |
| 20°F | Oct 31 | Nov 4 | Nov 9 | Nov 13 | Nov 16 | Nov 21 | Nov 26 | Dec 1 | Dec 9 |
| 16°F | Nov 10 | Nov 15 | Nov 20 | Nov 25 | Nov 29 | Dec 3 | Dec 8 | Dec 14 | Dec 25 |
Growing season length
Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | 171 | 165 | 161 | 157 | 154 | 151 | 146 | 141 | 135 |
| 32°F | 197 | 191 | 186 | 182 | 178 | 174 | 169 | 165 | 157 |
| 28°F | 228 | 220 | 215 | 210 | 206 | 201 | 197 | 192 | 184 |
| 24°F | 262 | 252 | 245 | 240 | 235 | 230 | 225 | 219 | 212 |
| 20°F | 296 | 285 | 277 | 271 | 265 | 259 | 253 | 246 | 236 |
| 16°F | 328 | 314 | 307 | 300 | 293 | 287 | 281 | 272 | 261 |
How often it gets that cold
The share of years with at least one night at or below each temperature.
- 36°F or colder
- 100% of years
- 32°F or colder
- 100% of years
- 28°F or colder
- 100% of years
- 24°F or colder
- 100% of years
- 20°F or colder
- 100% of years
- 16°F or colder
- 99% of years
Degree days
A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.
- Heating degree days, base 65°F
- 5,723
- Cooling degree days, base 65°F
- 690
- Growing degree days, base 40°F
- 5,072
- Growing degree days, base 45°F
- 3,866
- Growing degree days, base 50°F
- 2,836
- Growing degree days, base 55°F
- 1,966
- Growing degree days, base 60°F
- 1,247
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,088 | 0 | 0 |
| February | 833 | 0 | 1 |
| March | 668 | 0 | 14 |
| April | 420 | 2 | 90 |
| May | 185 | 33 | 318 |
| June | 58 | 93 | 485 |
| July | 7 | 264 | 722 |
| August | 10 | 233 | 688 |
| September | 101 | 65 | 416 |
| October | 445 | 2 | 99 |
| November | 809 | 0 | 4 |
| December | 1,100 | 0 | 0 |
What this means
NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.
The station is 16.1 km from George. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.
More
Sources
NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00456880 (Quincy). Public domain.